title: Copper(I) nitrosyls from reaction of copper(II) thiolates with S-nitrosothiols: mechanism of NO release from RSNOs at Cu.
abstract: S-nitrosothiols (RSNOs) serve as ready sources of biological nitric oxide activity, especially in conjunction with copper centers. We report a novel pathway for the generation of NO within the coordination sphere of copper model complexes from reaction of copper(II) thiolates with S-nitrosothiols. Reaction of tris(pyrazolyl)borate copper(II) thiolates (iPr2)TpCu-SR (R = C6F5 or CPh3) with (t)BuSNO leads to formation of (iPr2)TpCu(NO) and the unsymmetrical disulfide RS-S(t)Bu. Quantum mechanical investigations with B3LYP-D3/6-311G(d) suggest formation of a κ(1)-N-RSNO adduct (iPr2)TpCu(SR)(R'SNO) that precedes release of RSSR' to deliver (iPr2)TpCu(NO). This process is reversible; reaction of (iPr2)TpCu(NO) (but not (iPr2)TpCu(NCMe)) with C6F5S-SC6F5 forms (iPr2)TpCu-SC6F5. Coupled with the facile, reversible reaction between (iPr2)TpCu(NO) and C6F5SNO to give (iPr2)TpCu-SC6F5 and 2 equiv NO, we outline a new, detailed catalytic cycle for NO generation from RSNOs at Cu.
authors.affiliation: Department of Chemistry, Georgetown University , Box 571227-1227, Washington, DC 20057, United States.
authors.forename: Shiyu
authors.initials: S
authors.lastname: Zhang
authors.forename: Nihan
authors.initials: N
authors.lastname: Çelebi-Ölçüm
authors.forename: Marie M
authors.initials: MM
authors.lastname: Melzer
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Warren
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000008:administration & dosage* / Q000737:chemistry; D008958:Models, Molecular; D009569:Nitric Oxide / Q000008:administration & dosage* / Q000737:chemistry; D026403:S-Nitrosothiols / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D016166:Free Radical Scavengers; D026403:S-Nitrosothiols; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D003300:Copper